A total of 718 kg wet mass of seaweed (bladder wrack, Fucus vesiculosus) was collected from a coastline in the western part of the Baltic Sea (54°57' N, 11°59' E) between 11 and 27 July 2006 by the Risø National Laboratory, Denmark. The seaweed was first dried in open air and subsequently in heating cabinets at 85°C leaving a total dry mass of 105 kg. The sample was then ground into powder, sieved through a 250 μm mesh, homogenized by mixing in a nitrogen atmosphere, bottled in polyethylene sealed bottles (100g units) and coded as IAEA-446 (for a total of 900 bottles). All bottles were sterilized according to ISO standards at 25 kGy (60Co) in an irradiation facility.
This Certified Reference Material is intended to be used for quality assurance/quality control of the analysis of radionuclides in sediment samples, for the development and validation of analytical procedures and for training purposes.
Certified values for massic activities (Based on dry mass)
Reference date for decay correction: 01 August 2006
| Radionuclide | Certified value [Bq kg-1] | 95% Confidence interval [Bq kg-1] |
| 40K | 660 | 626 - 671 |
| 137Cs | 18.8 | 18.2 - 19.2 |
| 234U | 10.5 | 10.0 - 11.0 |
| 239+240Pu | 0.024 | 0.022 - 0.026 |
Information values for massic activities (Based on dry mass)
| Radionuclide | Information value [Bq kg-1] | 95% Confidence interval [Bq kg-1] |
| 90Sr | 5.1 | 4.5 - 5.3 |
| 99Tc | 14.8 | 13.8 - 20.2 |
| 210Pb(210Po)$ | 10.9 | 10.2 - 12.0 |
| 226Ra | 17.0 | 14.2 - 18.9 |
| 228Ra*# | 15.4 | 15.0 - 16.7 |
| 228Th*# | 15.0 | 12.6 - 15.5 |
| 230Th | 0.36 | 0.22 - 0.38 |
| 232Th | 0.38 | 0.30 - 0.46 |
| 235U | 0.44 | 0.27 - 0.52 |
| 238U | 9.34 | 8.98 - 10.96 |
| 239Pu | 0.014 | 0.012 - 0.015 |
| 240Pu | 0.010 | 0.009 - 0.014 |
$ 210Pb and 210Po are considered to be in equilibrium
* Reference date for decay correction is 1 April 2011
# Note: 228Ra and 228Th are not in equilibrium
The assigned values were established on the basis of statistically valid results submitted by 29 laboratories, including the IAEA’s Radiometrics Laboratory, Monaco, which had participated in an international interlaboratory comparison organized by the IAEA Environment Laboratories, Monaco, in 2010.
The details concerning all reported results as well as the criteria for qualification as a certified or information value may be found in the respective report (attached).
